1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to a semiconductor device which has a semiconductor substrate on a package substrate.
2. Description of the Related Art
In recent years, electronic equipment using a semiconductor device, for example, a cellular phone, is required to be thinner. In order to fulfill the demand for thinner electronic equipment, it is important to reduce an area for mounting a semiconductor device used in the electronic equipment. Therefore, in a semiconductor device of recent years, during the process of manufacturing the semiconductor device, a semiconductor substrate is ground to be thinner or an encapsulating resin for encapsulating the semiconductor substrate and the like is made thinner to reduce the area for mounting, for example.
Japanese Patent Application Laid-Open No. 2002-076206 discloses an exemplary configuration of a semiconductor device, which is illustrated in FIG. 13. In FIG. 13, a semiconductor device 1300 includes balls 1301, a substrate 1302 disposed on the balls 1301, projections 1303 disposed on the substrate 1302, a resin 1304 for covering the projections 1303, a chip 1305 disposed on the projections 1303, and an epoxy resin 1306 for encapsulating the chip 1305, the projections 1303, and the resin 1304. Japanese Patent Application Laid-Open No. 2002-076206 discloses a technology which may enhance the effect of exhausting heat generated by the chip 1305 by directly bringing the epoxy resin 1306 into contact with the chip 1305.
Japanese Patent Application Laid-Open No. Hei 9-040756 discloses a technology which adjusts the ingredients of an epoxy resin which is a resin for encapsulating a semiconductor device.
During the process of manufacturing a semiconductor device, it is necessary to mark an encapsulating resin for encapsulating a semiconductor substrate having a circuit for implementing a desired function formed thereon with the product number of the manufactured semiconductor device, the manufacturer name of the semiconductor device, or the like. The marking is carried out by irradiating the encapsulating resin with an infrared laser to engrave the product number, the manufacturer name, or the like. However, as described above, the encapsulating resin is getting thinner and thinner in semiconductor devices of recent years, and hence the applied infrared laser may passes through the encapsulating resin to reach the semiconductor substrate having the circuit formed thereon. Thus, there arises a problem in that the semiconductor device malfunctions under the influence of the infrared laser applied to the semiconductor substrate. The inventor of the present invention has confirmed by experiments that a semiconductor device, which operated normally before marking, malfunctioned after the marking. The inventor of the present invention thinks that, because of the infrared laser applied to the semiconductor substrate, heat is generated in the semiconductor substrate, the generated heat disconnects wiring of the circuit formed on the semiconductor substrate, and thus, the semiconductor device malfunctions.